Refrigerating machine



R. LLBERRY yREFRIGERA'JfI'NGf MACHINE July 1, 1936. v

Filed Dec. 5, 1934 His ther-'h eg.,

Patented July 7,- 1936 PATENT OFFICE 2,047,053 REFRIGERATTNG MACHINE Robert U. Berry, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 5, 1934, Serial No. '756,111

8 Claims.

inder and replaced by cooler gas at the same pressure, the hot gas being circulated through a heat exchange device where its temperature is lowered. The cooler gas is then expanded in the compressor and thereby further cooled and at the end of the expansion stroke is displaced through' operation of the scavenging pump by warmer gas which is returned from the cooling element of the refrigerating machine, the displaced cool gas being circulated at constant pressure to the cooling element from the compressor. During each scavenging operation, the compressed or the expanded gas is removed from the cylinder and replaced by gas at the same pressure but at a diiferent temperature. For ideal 'operation of the refrigerating machine, the scavenging should completely 4replace the gas in the cylinder with an exactly equal volume of scavenging gas without any mixing of replaced and scavenging gases. It is, therefore, desirable that this scavenging be accomplished in as short a time as possible with little mixing of the scavenging gas and the gas which has been acted on by the compressor.

Accordingly, it is an object of my invention to provide a' compressor for refrigerating machines of the type using a gaseous refrigerant without liquefaction which shall have an improved arrangement for scavenging.

Further objects and advantages of my invention will become apparent as the following description proceeds and thefeatures of `novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification. V

For a better understanding of my invention, reference may be had to the accompanying drawing, in which Fig. 1 shows diagrammatically a refrigerating system utilizing a compressor and embodying my invention, the compressor being shown in the high pressure scavenging position; and Fig. 2 shows the compressor of Fig. l 'in the 5 low pressure scavenging position.

(Cl. (i2- 136) Referring now to the drawing in Fig. 1, I have shown a refrigerating system of the type in which a gaseous -refrigerant is circulated without liquefaction. This system comprises a compressor Ill,

a heat dissipating coil Il, which is air or water 5 cooled, for removing heat from the compressed gas, and a refrigerating coil I 2 for absorbing heat from a. medium to be cooled. The coil il is arranged in the high pressure circuit of the system and the coil I2 is arranged in the low pressure 10 circuit of the system, scavenging fans or pumps i 3 and I4 being arranged to circulate the gas through the high and low pressure circuits respectively. During the operation of the compressor l0, the compressed gas discharged there- 15 from is at a higher temperature than the gas cooled in the coil il, which replaces the compressed gas during the scavenging operation. It will thus be seen that the weight of the replacing gas willbe greaterA than that of the replaced gas 20 since both occupy the same volume in the compressor. At the other end of the stroke cold expanded gas is replaced by warmer gas at the same pressure. The gas remaining in the cylinder at the end of the scavenging operation, 25 therefore, has less weight than the removed gas,

so that during the operation of the compressor, gas is continually removed from the high presl sure side and added to the low pressure side. In `order to compensate for this pumping of gas to 30 the low pressure side, another compressor i5 is provided to pump gas from a connection i6 on the low pressure side at the warm end ofy the refrigerating coil |12 to the connection il on the high pressure side at the hot end of the coil il.

It is desirable, as has been pointed out, that during the scavenging operation the gas blown through the cylinder should circulate through the cylinder from one port to the other, with minimum turbulence and little mixing of the gas 40 within the cylinder and the replaced gas. An ideal condition would be attained if there were no mixing whatsoever and the gas in the cylinder were replaced as a body by an equal volume of gas from the scavenging port.'

In accordance with my invention, I provide a baflle within the compressor so arranged that the passage of the scavenging gas flowing through the compressor is of substantially uniform cross-section and having an area substantially equal to that of the ports. In the particular embodiment of my invention shown, the compressor It comprises a cylinder it provided with low pressure ports i9 and it, and with high pressure ports 21| and 22. Within the cylinder it is arranged a 55 reciprocating piston 23 driven by a suitable power device through a reciprocating shaft 23a. The piston 23 is provided with a hollow cylindrical extension 2li. When the piston is in the position shown, the end of the extension 2d closes the ports i9 and lies within an annular recess 25 formed by a cylindrical portion 2li extending inwardly from the head of the cylinder it. Ports 2V and 28 are provided in the extension 2S near the body of the piston 23, and, in the position shown in Fig. 1, these ports register with the ports 2l and 22 respectively in the cylinder. The piston is shown in its position during the scavenging operation at the end of the compression stroke. Scavenging gas is forced by the fan it through the coil ll where it is cooled, then through a conduit 29 to the port 2l, through the port 2l into the cylinder lli and forces the compressed gas out of the cylinder through the ports 28 and 22, and thence to the fan I3 through a conduit 30, as indicated by the arrows in the drawing. The hot compressed gas is thus replaced by cooled gas at substantially the same pressure. In order to provide a path of uniform cross-Sectional area for the scavenging gas, I provide a bale .il formed at the end of the body portion of' the piston 23 and extending partially within the cylindrical portion 2B, the bafe extending completely across the cylinder midwaybetween the ports 2l' and 28. The chamber formed between the cylinder and the piston at the end of the compression stroke is of U-shape cross-section and of substantially the same area as that of the ports 2 and 2li. When the scavenging gas passes through the cylinder there will be a minimum of turbulence and mixing of the scavenging and the replaced gas. From the position shown, the piston. 23 moves to the right toward the other end ofv its stroke, the ports 2l and 22 are closed by the cylindrical portion 24 and the gas is expanded. At the end of this expansion stroke, the ports i9 are uncovered by the cylindrical portion 2d of the piston 23 and the ports 2d register with the ports 2l! and 2t, as Shown vin Fig. 2. The cold gas within the cylinder is then forced out through the ports 2li by operation oi the fan lil, which blows scavenging gas warmed in cooling coil l2 and at substantially the same pressure through a conduit 32 and the ports lli into the cylinder. 'Ihe cooled expanded gas ows through a conduit 33 to the refrigerating coil l2 Where it is warmed upon absorption of heat from the medium to be cooled. The ports l@ have a total area substantially equal to that of the cyly inder cross-sectional area, and the sum oi' the areas of the ports 21 and 2t is also substantially equal to the cylinder cross-sectional area. 'There is, therefore, a minimum mixing and turbulence of the low pressure gas passing through the cylinder.

During the operation of the refrigerating machine herein described the piston 23 and the scavenging fans are operated continuously to deliver hot compressed gas to the high pressure circuit and cold expanded gas to the low pressure circuit. The hot compressed gas delivered to the high pressure circuit by the scavenging operation is cooled in the coil ll which may be arranged so that a cooling medium such as water or air circulates thereover and the cooled gas from the high pressure circuit is then delivered to the compressor Ill where it is expanded and cooled. The cold gas is delivered to the coil l2 by the scavenging operation and absorbs heat acerbes from the medium surrounding the coil, and when it has been warmed by this absorption of heat is returned to the compressor to complete the cycle of the refrigerating machine. The compressor l5 is operated continuously to maintain the desired pressure difference between the high and low pressure circuits. 'I'he dimensions of the ports and the arrangement of the baie Si and the cylindrical extension 2li are such that the scavenging gas forces out the-gas within the l cylinder substantially as a body and, therefore, with very little mixing of the scavenging gas and the gas in the cylinder. The losses due to mixing of gases at diiferent temperatures are thereby minimized, and the efficiency of the scavenging operation is greatly improved.

It will be evident from the foregoing that l have provided a compressor for refrigerating systems in which gaseous refrigerant is compressed without liquefaction, which is so constructed that the scavenging operation will be eiectedvwith a minimum turbulence and mixing of the scavenging gas and the replaced gas.

While I have shown a particular embodiment of my invention, other modifications will be apparent to those skilled in the art. l. do not, therefore, desire my invention to be limited to the specific construction shown and described and I intend in the appended claims to cover all modications within the spirit and scope of my invention.

What claim as new and desire to secure 'oy Letters Patent of the United States is:

l. In a refrigeratin'g machine in which a gaseous refrigerant is utilized without liqueiaction. a compressor comprising a cylinder having inlet and exhaust ports, a piston within said cylinder, means operable upon the opening of said intake and exhaust ports for scavenging the gas from said cylinder, and means within said cylinder for providing a passage of substantially uniform cross-sectional area for said scavenged gas flowing between said ports.

2. In a refrigerating machine in which a gaseous refrigerant is utilized without liquefaction. a compressor comprising a cylinder having inlet and exhaust ports, a piston within said cylinder, means operable upon the opening of said intake and exhaust ports for scavenging the gas from said cylinder, and means including a baffle secured to said piston for providing a passage of substantially uniform cross-sectional area for said scavenged gas flowing between 'said intake and exhaust ports.

3. In a refrigerating machine in which a gas is expanded and compressed without liquefaction, a compressor comprising a cylinder having intake and exhaust ports, and means including a piston for compressing gas within said cylinder. means for scavenging the compressed gas from said cylinder, and means within said cylinder for providing a passage of substantially uniform cross-sectional area for said scavenged gas owing between said ports.

4. In a refrigerating machine in which a gas is expanded and compressed without liquefaction, a compressor comprising a cylinder having high pressure intake and exhaust ports and low pres- CTI sure intake and exhaust ports, means including a sage of substantially uniform cross-sectional arca I5 for said scavenged gas owing between said intake and exhaust ports.

In a refrigerating machine in which a gas is expanded and compressed without liquefaction, a compressor comprising a cylinder having a low pressure intake port at one end and a low pressure exhaust port at the other end, said cylinder also having high pressure intake and exhaust ports intermediate said low pressure intake and exhaust ports, means including a piston for compressing gas in said cylinder, means for closing said W pressure ports on the compression stroke of said piston, means admitting high pressure gas to said cylinder for scavenging said compressed gas near the end of said compression stroke, and means `including a baille on said piston for providing a passage of substantially uniform cross-sectional area for said scavenging gas between said high pressure ports.

6. In a refrigerating machine in which a gas is expanded and compressed Without liquefaction, a compressor comprising a cylinder having a low pressure intake port at one end and a low pressure exhaust port at the other end, said cylinder having high pressure intake and exhaust ports intermediate said low pressure intake and exhaust ports, means including` a piston for com- 'pressing gas in said cylinder, means including a hollow cylindrical extension on said piston for closing said low pressure ports on the compression stroke of said piston, theother of said low pressure ports being closed by said piston, means admitting high pressure gas to said cylinder forscavenging said compressed gas ne'ir the end cf said compression stroke, and means including a baille on said piston for providing a passage for said scavenging gas having a substantially uniform cross-sectional area.

7. In a refrigerating machine in which a gas is expanded and compressed without liquefaction, a compressor comprising a cylinder having a low pressure intake port at one end and a low pressure exhaust port at the other end, said cylinder also having high pressure intake and exhaust ports intermediate said low pressure intake and exhaust ports, means including apiston for compressing gas in said cylinder, means including a hollow cylindrical extension on said piston for closing said low pressure ports on the compression stroke of said piston, the other of said low pressure ports being closed byv said piston, means admitting high pressure gas to said cylinder for scavenging said compressed gas near the end of said compression stroke, and means including a bale and an annular channel at one end of said cylinder for providing a passage for said scavenging gas of substantially uniform cross-sectional area, a substantial portion of said cylindrical extension lying Within said channel at the end of the compression stroke of said ypiston.

8. In a refrigerating machine in Whicha gas is expanded and compressed without liquefaction, a compressor comprising a cylinder having high pressure intake and exhaust ports and low pressure intake and exhaust ports, means including a piston for compressing gas within said cylinder, means for scavenging compressed gas from said cylinder near the end of the compression stroke of said piston, means for scavenging expanded gas from said cylinder'near the end of the expansion stroke of said piston, `and means including a baiiie on saidv piston for providing. a. passage of substantially' uniform cross-sectional area for said scavenging gas between said high pressure intake and exhaust ports, the path of said scavenging gas at the end of said compression stroke and at the end of said expansion stroke being of substantially the same cross-sectional area as the high pressure ports and the low pressure ports respectively.

ROBERT U. BERRY. 

